Pakistan is going after "wrong terrorists", the US has said and accused it of failing to tackle the insurgent networks posing the greatest threat to Nato forces in Afghanistan.

America's ambassador to Pakistan Annee Patterson has said that failure to agree on common targets was hampering the struggle against the Taliban in Afghanistan.

Patterson said America and Islamabad have agreed on tackling al-Qaida's leadership and the Pakistani Taliban, according to a report in the 'Daily Telegraph'.

"Where we differ, of course, is the treatment of the groups who are attacking our troops in Afghanistan," she was quoted as saying by the newspaper.

"And that comes down to Haqqani and Gul Bahadur and Nazir, to a lesser extent Hekmatyar, and yes of course there are differences there."

Gul Bahadur and Maulvi Nazir are Pakistani Taliban commanders who fight only in Afghanistan. Gulbuddin Hekmatyar is a veteran Afghan warlord who is based close to the Pakistani border.

The Haqqani network is blamed for a series of bombings inside Kabul.

Both Hekmatyar and Haqqani once had close ties to Pakistan's Inter-Services Intelligence agency, while Islamabad saw Mullah Omar's regime in Afghanistan as a key ally until the 9/11 attacks.